This invention relates generally to air cleaners or filters and more particularly relates to air cleaners with cylindrical, pleated paper filter elements used primarily with over-the-road trucks and agricultural tractors. In such air cleaners, the air is drawn into a housing and radially inwardly through the filter element for axial discharge therefrom. The cylindrical air filter element is sealed within the housing so that all air entering the housing must pass through the walls of the filter element.
In the prior art, sealing of the filter element in the housing has been accomplished by compressing the outlet end of the filter element against the end wall of the housing, and by providing a gasket between the end of the filter element and the housing end wall. An example of this is shown in the Anderson et al. U.S. Pat. No. 3,078,650, issued Feb. 26, 1963, in which a yoke assembly cooperating with a threaded wing bolt and nut is used to compress the filter element against the end wall of the housing to prevent leakage of air around the filter element. Various other latches and clamping devices have been used to effect a positive clean air seal in such filter assemblies. Using such state of the art axial compression sealing techniques requires filter elements constructed so as not to collapse under compression, and requires the use of relatively heavy-gauge steel in the housing to withstand the pressures. Because both the filter housing and the filter element must be strong and rigid when using such techniques, improvements in the area of low-cost, lightweight elements and housings have been hampered. With respect to the housings, non-engineering grades of plastics as well as some molding processes could not be safely utilized.